1. Field of the Invention
The present invention relates to telecommunications and, more particularly, to functions of a voice command platform.
2. Description of Related Art
A voice command platform provides an interface between speech communication with a user and computer-executed voice command applications. Generally speaking, a person can call a voice command platform from any telephone and, by speaking commands, can browse through navigation points (e.g., applications and/or menus items within the applications) to access and communicate information. The voice command platform can thus receive spoken commands from the user and use the commands to guide its execution of voice command applications, and the voice command platform can “speak” to a user as dictated by logic in voice command applications.
For instance, a person may call a voice command platform, and the platform may apply a voice command application that causes the platform to speak to the user, “Hello. Would you like to hear a weather forecast, sports scores, or stock quotes?” In response, the person may state to the platform, “weather forecast.” Given this response, the application may cause the platform to load and execute a subsidiary weather forecasting application. The weather forecasting application may direct the platform to speak another speech prompt to the person, such as “Would you like to hear today's weather or an extended forecast?” The person may then respond, and the weather forecasting application may direct the voice command platform to execute additional logic or to load and execute another application based on the person's response.
A robust voice command platform should therefore be able to (i) receive and recognize speech spoken by a user and (ii) provide speech to a user. The platform can achieve these functions in various ways.
On the incoming side, for instance, the platform may include an analog-to-digital (A-D) converter for converting an analog speech signal from a user into a digitized incoming speech signal. (Alternatively, the user's speech signal might already be digitized, as in a voice-over-IP communication system, for instance, in which case A-D conversion would be unnecessary). The platform may then include a speech recognition (SR) engine, which functions to analyze the digitized incoming speech signal and to identify words in the speech. The SR engine will typically be a software module executable by a processor.
Usually, a voice command application will specify which words or “grammars” a user can speak in response to a prompt for instance. Therefore, the SR engine will seek to identify one of the possible spoken responses. (Alternatively, the SR engine may operate to identify any words without limitation).
In order to identify words in the incoming speech, the SR engine will typically include or have access to a dictionary database of “phonemes” (small units of speech that distinguish one utterance from another). The SR engine will then analyze the waveform represented by the incoming digitized speech signal and, based on the dictionary database, will determine whether the waveform represents particular words. For instance, if a voice command application allows for a user to respond to a prompt with the grammars “sales,” “service” or “operator”, the SR engine may identify the sequence of one or more phonemes that makes up each of these grammars respectively. The SR engine may then analyze the waveform of the incoming digitized speech signal in search of a waveform that represents one of those sequences of phonemes. Once the SR engine finds a match, the voice command platform may continue processing the application in view of the user's spoken response.
Additionally, the SR engine or an ancillary module in the voice command platform will typically function to detect DTMF tones dialed by a user and to convert those DTMF tones into representative data for use in the execution of a voice command application. Thus, for instance, a voice command application might define a particular DTMF grammar as an acceptable response by a user. Upon detection of that DTMF grammar, the platform may then apply associated logic in the application.
On the outgoing side, the voice command platform may include a text-to-speech (TTS) engine for converting text into outgoing digitized speech signals. In turn, the platform may include a digital-to-analog (D-A) converter for converting the outgoing digitized speech signals into audible voice that can be communicated to a user. (Alternatively, the platform might output the digitized speech signal itself, such as in a voice-over-IP communication system).
A voice command application may thus specify text that represents voice prompts to be spoken to a user. When the voice command platform encounters an instruction to speak such text, the platform may provide the text to the TTS engine. The TTS engine may then convert the text to an outgoing digitized speech signal, and the platform may convert the signal to analog speech and send it to the user. In converting from text to speech, the TTS engine may also make use of the dictionary database of phonemes, so that it can piece together the words that make up the designated speech.
Also on the outgoing side, a voice command platform may include a set of stored voice prompts, in the form of digitized audio files (e.g., *.wav files) for instance. These stored voice prompts would often be common prompts, such as “Hello”, “Ready”, “Please select from the following options”, or the like. Each stored voice prompt might have an associated label (e.g., a filename under which the prompt is stored). By reference to the label, a voice command application might specify that the voice command platform should play the prompt to a user. In response, the voice command platform may retrieve the audio file, convert it to an analog waveform, and send the analog waveform to the user.
A voice command application can reside permanently on the voice command platform, or it can be loaded dynamically into the platform. For instance, the platform can include or be coupled with a network or storage medium that maintains various voice command applications. When a user calls the platform, the platform can thus load an application from the storage medium and execute the application. Further, in response to logic in the application (such as logic keyed to a user's response to a menu of options), the platform can load and execute another application. In this way, a user can navigate through a series of applications and menus in the various applications, during a given session with the platform.
A voice command application can be written or rendered in any of a variety of computer languages. These applications and the documents they contain are generally in the form of voice-markup files. One language for creating these voice markup files is VoiceXML (or simply “VXML”), which is a tag-based language similar the HTML language that underlies most Internet web pages. (Other analogous languages, such as SALT, SpeechML and VoxML for instance, are available as well.) By coding a voice command application in VXML, the application can thus be made to readily access and provide web content, just as an HTML-based application can do. Further, when executed by the voice command platform, the VXML application can effectively communicate with a user through speech.
An application developer can write a voice command application in VXML. Alternatively, an application developer can write an application in another language (such as Java, C, C++, etc.), and the content of that application can be rendered in VXML. (For instance, when the platform loads an application, the platform or some intermediate entity could transcode the application from its native code to VXML.)
Voice command applications can be made up of voice-markup files or documents. In order for a voice command platform to execute an application or other tag-based application, the platform should include a browser or “interpreter.” The browser can interpret voice-markup files and make them available to the user. More specifically, the browser functions to interpret tags set forth in the application and to cause a processor to execute associated logic set forth in the application.
A VXML application can be made up of a number of VXML documents, just like an HTML web site can made up of a number of HTML pages. A VXML application that is made up of more than one VXML document should include a root document, somewhat analogous to an HTML home page. According to VXML, the root document defines variables that are available to all subsidiary documents in the application. Whenever a user interacts with documents of a VXML application, the root document of the application is also loaded. Therefore, variables defined in the root document should be available during execution of any of the documents of the application.
Each VXML document will include a <vxml> tag to indicate that it is a VXML document. It may then include a number of <form> sections that can be interactive (e.g., prompting a user for input) or informational (e.g., simply conveying information to a user.) Within a given form, it may further include other executable logic.
A VXML document can also define grammars as described above. In particular, VXML grammars are words or terms that the VXML application will accept as input during execution of the application. When a VXML application is executed on a voice command platform, the platform may provide the SR engine with an indication of the grammars that the VXML application will accept. Once the SR engine detects that a user has spoken one of the grammars, the platform may apply that grammar as input to the VXML application, typically proceeding to execute a set of logic (e.g., a link to another document) in response.
For example, a VXML document can define as grammars a number of possible options, as well as a number of possible words that a user can speak to select those options. For instance, a document might define as options of clothing the items “hat”, “shirt”, “pants” and “shoes”. In turn, the document might define the following as acceptable grammars for the “hat” option: “hat”, “visor”, “chapeaux” and “beret”.
Grammars defined in the root document of a VXML application are, by default, available for use in all of the subsidiary documents of the application. Thus, when a voice command platform is executing a VXML application, if a user speaks a grammar that is defined in the root document of the application, the voice command platform should responsively execute the logic that accompanies that grammar in the root document of the application.
In a voice command platform, each navigation point may have a respective identifier or label. For example, each voice command application can have a respective label, such as a network address where the application is maintained. As another example, a voice command application can define a number of successive menus through which a user can browse, and each menu might have a respective label by which it can be referenced. A voice command platform can use these labels to move from application to application or from menu item to menu item, just as hyperlinks operate to cause a browser to move from one web page (or component of one web page) to another.
In VXML, for instance, each VXML document will have a respective Universal Resource Identifier (URI), which is akin to a Universal Resource Locator (URL) used to identify the network location of an HTML page. A given VXML document may thus define logic that instructs the voice command platform to load and execute another VXML document from a designated URI. For instance, a VXML document may indicate that, if a user speaks a particular grammar, the platform should load and execute a particular VXML document from a designated URI, but that, if the user speaks another grammar, the platform should load and execute another VXML document from another designated URI. In addition, a VXML document may also specify navigation points that are not in a VXML URI format. Objects associated with these navigation points will not generally be voice-markup files and, thus, can not be directly interpreted by the VXML browser. For example, many VXML documents specify audio files. These audio files are generally formatted *.wav files or u-law files and not as voice-markup files. But for the fact that these audio files are specified in a voice-markup file, the browser would not be able to properly interpret them.
An example of a VXML application is a weather reporting application. The weather reporting application may have a root document that includes a tag defining a welcome message and prompting a user to indicate a city or zip code. The root document may further set forth a bundle of grammars that are possible city names and corresponding zip codes that a user can speak in response to the prompt.
When the voice command platform executes this root document, it may thus send the welcome message/prompt to the TTS engine to have the message/prompt spoken to the user. In turn, when the user speaks a response, the SR engine would identify the response as one of the acceptable grammars. The platform would then continue executing the root document in view of the spoken response.
The root document might next prompt the user to indicate whether the user would like to hear today's weather or an extended forecast, and the user would again speak a response. In turn, the root document might indicate that, if the user selects “today's weather,” the platform should load and execute a subsidiary document from a designated URI, and if the user selects “extended forecast,” the platform should load and execute a different subsidiary document from another designated URI. Of course, many other examples of VXML applications are possible as well.
In most cases, a platform provider will own and operate the voice command platform. Content providers (or independent application developers having a relationship with a content provider for instance) will then provide the VXML applications to be executed by the platform. The platform provider may also provide some applications for the platform and may therefore function as a content provider as well.
Further, a content provider or other application developer can personalize a VXML application, through reference to user profiles. For example, a telecommunications service provider (e.g., local exchange carrier or interexchange carrier) can provide a voice-activated-dialing (VAD) application that allows users to dial a telephone number by speaking a name. To support this feature, the VAD application may direct the voice command platform to prompt a user for a user ID or to determine the user ID based on calling number identification provided when the user's call was connected to the platform. The VAD application may then instruct the platform to call up a personalized VAD application (through use of Microsoft Active Server Pages, for instance), which is tied to the user's personal address book. Each name in the address book may then define an acceptable grammar. When the user speaks one of the names, the application may cause the platform to retrieve a corresponding telephone number and to provide that number to a network switch to facilitate initiating the call.